The recF gene is required for two basic genetic processes, genetic recombination and DNA repair. The major question about recF centers on whether it functions in a regulatory capacity controlling these processes or whether it has an enzymatic activity needed to carry out these reactions. Our studies of suppression of recF by several recA mutations suggests that the recF gene product functions primarily by modulating recA activity. It appears that two recF-dependent changes in recA activity normally occur in response to DNA damage. The first results in activation of the recA-dependent proteolytic activity required for induction of the SOS pathways of DNA repair. The second allows recA to carry out the RecF pathway of recombination and recombinational DNA repair. These two changes in recA activity are separable by mutation since the srfA mutation of the recA gene restores only RecF recombination without concomitant restoration of SOS induction in recF mutant strains.